I found a photo of some Mangalitsa pigs in Hungary, in a giant dirt lot. They've removed all vegetation in their pen.
The photo illustrates a few things about pigs: they eat everything. Also, you can give them a lot of space , but they'll group together very closely. E.g. the ones in the background are packed in very tight, like Mark Baker's pigs:
Obviously his need more time to destroy everything, there's still some green stuff in the pen.